Extract Huawei E3131s-6 Firmware 21.158.00.00.1020.B757 on your computer
Install the Firmware update file for Huawei E3131s-6 downloaded from Huaweiflashfiles.com
Follow the procedure for updating Firmware that is given in Package.

Huawei Flash File | Size: 8.13 MB
Version: 21.158.00.00.1020.B757
Operator: iiNet Australia
Operating systems: Windows 7/8/10/XP/Vista
Huawei E3131s-6 Firmware Download